Secondary forests that regrow after agricultural land has been abandoned now comprise more than half of the forest area worldwide, and particularly in the Tropics the role of secondary forests in the carbon cycle remains uncertain.
Secondary forests rapidly sequester carbon, but rates of accumulation vary with forest age and with environmental conditions. In young forests, carbon accumulation is very quick, but accumulation rates are lower in older secondary forests. Overall, carbon accumulation is faster in wet than in dry tropical forests (Poorter et al. 2016). To estimate rates of carbon accumulation in secondary tropical forests at a continental scale, and thus the size of the carbon sink in regrowing forests, a wall-to-wall estimate on forest age is crucial.
In this project, you will use existing datasets to assess to what extent forest age can be predicted in the Neotropics. You will construct models of forest age based on the timing of forest cover loss estimated from remote-sensing data (Hansen et al. 2013), environmental conditions, and mapped aboveground biomass (e.g. Baccini et al. 2012, Avitabile et al. 2016) using machine learning. The age map will be validated using an extensive dataset of field data on forest age across the Neotropics.
- Modelling secondary forest age based on existing information on forest cover loss, environmental variables, and aboveground biomass, using machine learning techniques.
- Validation of the map using forest plot data from tropical secondary forests.
- Comparison with an existing age map for the Neotropics (Chazdon et al. 2016).
- Avitabile V et al. (2016) An integrated pan-tropical biomass map using multiple reference datasets. Global Change Biology 22:1406-1420.
Baccini A et al. (2012) Estimated carbon dioxide emissions from tropical deforestation improved by carbon-density maps. Nature Climate Change 2:182-185.
- Chazdon RL et al. (2016) Carbon sequestration potential of second-growth forest regeneration in the Latin American tropics. Science Advances 2:e1501639.
- Hansen MC et al. (2013) High-resolution global maps of 21st-century forest cover change. Science 342:850-853.
- Poorter L et al. (2016) Biomass resilience of Neotropical secondary forests. Nature 530:211-214.
- Analytical skills
- Interest in spatial analysis
- Scripting skills (in R) would be useful
Theme(s): Modelling & visualisation, Integrated Land Monitoring